Very Easy Mode

At the title screen where you have the option of game modes, highlight Golden Playhouse and hold select until the screen flashes white. You must do this every time you start or load your game to have an effect.

Colosseum Mode

How to view all eight endings

Catherine has eight different endings, and which one you get depends on where your Karma meter is by stage nine and your responses to the final four questions asked during that stage. The first of the four questions is inconsequential, but the others determine the ending.

Unlockable

How to Unlock

Bad Cheater's Ending

Answer "Yes" to Question 2, "Yes" to Question 3, and "Chaotic Excitement" to Question 4. Your Karma meter needs to be in the blue.

Bad Lovers' Ending

Answer "Yes" to Question 2, "Yes" to Question 3, and "Peaceful Days" to Question 4. Your Karma meter needs to be in the red.

Good Cheater's Ending

Answer "Yes" to Question 2, "Yes" to Question 3, and "Chaotic Excitement" to Question 4. Your Karma meter needs to be in the red.

Good Freedom Ending

Answer "No" to Question 2, "No" to Question 3, and "Yes" to Question 4. Your Karma meter needs to be in either the red or blue.

Good Lovers' Ending

Answer "Yes" to Question 2, "Yes" to Question 3, and "I'm Ready" to Question 4. Your Karma meter needs to be in the blue.

True Cheater's Ending

Answer "No" to Question 2, "Yes" to Question 3, and "Yes" to Question 4. Your Karma meter needs to be in the red.

Secrets

Stage Skip

Clear all the stages in a chapter with a gold trophy on each stage (consecutively) to get a gold trophy for the chapter. Now, if you replay the chapter, you can press start and skip any of the stages in the chapter, including the boss. This is particularly useful when going for all the endings, especially for the last chapter. Stage skip for a chapter can only be unlocked by getting the gold trophy on Normal difficulty or above.
To get a gold trophy on a stage, you generally need to get all the gold coins and have a full step combo from the start of the stage to the end. Step combos don't continue if you die and restart at a checkpoint, so if you are going for a gold trophy and you die, then you need to restart at the beginning of the stage.

Unlimited Step Combo

When trying to beat whole levels in one step combo, you might find it hard to keep a consistent combo. So when you combo bar is almost fully drained, pressing undo will reset the whole bar giving you a better chance at beating the level in one combo!

Area/Level Hints

99 Retries

On level 4-1 when you start off you will notice there is a retry pillow in front of you. Get the pillow and right after press Start and retry the level. Do this as many times as you want until you hit the limit of 99 retries.